Human Alpha 2 nd Beta globin genes cloned in special circular DNA vector molecules have been inserted into eukaryotic tissue culture cells. The Alpha 2 gene is efficiently transcribed from these vectors, apparently irrespective of vector structure, while the vector remains extrachromosomal. In contrast, transcription of the Beta globin gene occures only in vectors containing a sequence from the SV40 genome which consists of 72 nucleotides repeated twice in tandem near the early SV40 promotor and which is known to be required for early SV40 transcription. The effect of this SV40 sequence on transcription of the Beta globin gene appears complex, being affected by distance from the Betal globin promotor, perhaps by orientation of the SV40 sequence with respect to the Beta globin gene, and apparently by concurrent replication of the vector within recipient cells. The proposed research is directed in part at further characterizing the interaction between the SV40 72 nucleotide repeats and the human Beta globin gene. In addition, experiments will be carried out to determine if the Alpha 2 globin gene or its flanking DNA contains a sequence functionally equivalent to the SV40 72 nucleotide repeats in activating transcription of other genes, as is suggested by at least some preliminary daa. Another goal of the proposed research is to determine what portion of the Alpha globin gene and/or its flanking DNA makes transcription of this gene independent of the SV40 72 nucleotide repeats. Human globin genes other than Alpha 2 and Beta will also be screened in this transcription system to determine if globin genes can be sorted into those that behave similarly either to Alpha 2 or Beta in regard to transcription augmentation by the SV40 72 nucleotide repeats, or if any these genes exhibit other distinct patterns of transcriptional behavior. Already, it has been determined that transcription of the human Delta globin gene seems to be augmented similarly to Beta globin genes, although the level of transcription in similar vectors is only a few percent of that seen with the Beta globin gene, roughly corresponding to relative levels of the two globins found in normal ervthrocytes. Experiments will be performed to determine which portion of the Delta gene is responsible for reduced levels of Delta mRNA. Finally, attempts will be made to isolate a region of DNA from the human chromosome 11 surrounding the Beta globin gene locus to determine if normal in vivo Betal globin transcription requires a distantly linked transcription augmenting function. The data obtained so far and the answers sought by the proposed studies relate specifically to the regulation of human globin synthesis and diseases associated with abnormal globin production, as well as to eukarvotic gene expression in general.